Self charging behaviour of electrolyte capacitors

When a capacitor initally charges its dielectric material's structure is "stressed" or polarised due to the presence of the electric field. This causes a small amount of energy to be stored in the inter-molecular bonds with in the dielectric material. When the capacitor discharges rapidly, the dieletric material's structure is still under stress even though the potential across the terminals is 0 due to its slower response. As it reverts back to its normal, minimal-energy state in the absence of an electric field, a small increase in electric potential develops across the capacitor's terminals after some time. If the dielectric material is held by an electric field for a long period of time the internal structure will re-arrange graduly itself as to achieve minimal-energy under influence. Thus when discharged after a long time with in an electric field the self-charging effects are smaller as a lower amount of stress is present in the molecular structure.

Extracted from my personal research into this topic.
Cheers,
Steve